In recent years, small portable devices have been spread worldwide, and at the same time, there has been a great and rapid demand for high-speed and large-capacity nonvolatile memories in accordance with the significant development in high-speed information transmission networks. For instance, NAND flash memories have rapidly evolved in recording capacity and have constituted a large market as storage memories. However, the NAND flash memories are significantly lower in operating speed than volatile memories, such as DRAMs or SRAMs.
In view of the above, attention has been paid to a resistance change memory (ReRAM) as a nonvolatile RAM that has substantially the same operation speed as the nonvolatile memories. The resistance change memory can be made to have a large capacity, using a three-dimensional array, and can store data in a nonvolatile manner. Therefore, it offers promising prospects when it is used as a work memory for, in particular, a system, such as a small portable device, for which low energy consumption is required. However, to exploit this feature, it is necessary to contrive the array and/or transistor structure.